Permanent magnet generators of the type having a rotor made up of two relatively movable permanent magnet assemblies have been proposed generally to provide for voltage regulation in response to changes in loading on the generator. They have also been employed for regulating voltage to compensate for changes in the rate of rotor rotation.
Examples of such proposals can be found in U.S. Pat. Nos. 3,233,133 issued Feb. 1, 1966 to Kober; 3,713,015 issued Jan. 23, 1973 to Frister; and 4,305,031 issued Dec. 8, 1981 to Wharton. Typical of these constructions is an arrangement wherein one of the permanent magnet assemblies is rigidly affixed to the rotor shaft and the other is rotatable relative thereto. By effecting relative rotation between the two permanent magnet assemblies, the output voltage of the generator may be varied, as described more fully in the previously identified patents, to achieve voltage regulation.
Though such systems should work well in theory, in practice, particularly in high speed generators, difficulty in effecting close regulation of the output voltage may be encountered. In particular, loading of the rotor components due to centrifugal force and other operational factors may render it difficult to achieve relatively precise angular adjustment of the movable permanent magnet assembly with respect to the fixed permanent magnet assembly. To the extent that precise adjustment is hindered, good control cannot be achieved.
The present invention is directed to overcoming the above problem.